package com.yu.lb;

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

@Component
public class MyLB implements LoadBalanced{
    //一个原子类的int型
    private AtomicInteger atomicInteger = new AtomicInteger(0);

    public final int getAndIncrement(){
        int current;
        int next; //表示第几次访问
        do{
            current = this.atomicInteger.get(); //
            next = current >= Integer.MAX_VALUE ? 0 :current + 1;
        }while (!this.atomicInteger.compareAndSet(current,next)); //如果相同为true，不同则将next的值给到current
        System.out.println("next:" + next);
        return next;
    }

    @Override
    public ServiceInstance instances(List<ServiceInstance> serviceInstances) {
        int index = getAndIncrement() % serviceInstances.size();

        return serviceInstances.get(index);
    }
}
